1. Field of the Invention
The present invention relates generally to control of a printing device, and more particularly, to provide drop volume normalization in an ink jet printing operation.
2. State of the Art
Printing devices, such as ink jet printing devices, are well known and available from such manufacturers as, for example, Hewlett Packard and NCAD. A typical ink jet printing device includes plural print heads, each of which includes a plurality of ink jet nozzles for printing in a given color of ink. Different print heads can be provided for different colors. The plural ink jet nozzles associated with a given color of printing ink can be displaced from one another in a vertical direction. As the printing device is repeatedly scanned back and forth across a printable medium, such as a paper sheet, the ink jet nozzles of the various print heads are activated to lay drops of ink on the sheet at precise locations. In typical color printing, between four and six different colors of ink are laid down over an area by successive heads, in successive scans across the sheet.
The ink jet nozzles of the print head or heads use very fine ink sprays to produce drops that collectively represent an image on a sheet being printed. Multiple print head arrangements, for producing multicolor images using such colors as cyan, magenta, yellow and black, are precision mounted relative to one another in the print device so that ink drops can be laid down on the sheet in precise locations. As mentioned previously, the print device is typically located on a movable carriage that scans back and forth above the sheet. Relative vertical movement between the print device and the sheet is provided between each scan, so that a different portion of the sheet can be printed during each scan. As those skilled in the art will appreciate, the nozzles on each of the multiple print heads must be controlled to lay down ink drops in precise locations relative to drops laid down by the other print heads.
Ink jet printing devices are often used to produce high quality, high resolution images on wide webs of paper at fast printing rates. To maintain quality as high as possible, accurate control of paper feed and scanning speed are necessary. Further, to produce high resolution images which do not include visible horizontal differences, typically referred to in the industry as "banding" effects, it is important that all ink drops laid on the sheet by the print device be accurate placed in a predetermined location on the sheet. To address banding, it is further important to control the drop volume output by each ink jet nozzle so that all printed drops on the sheet are consistent in size.
Accordingly, it would be desirable to enhance the control of the ink jet nozzles in an ink jet print device to further alleviate banding effects, and thus enhance the quality and resolution of a reproduced image.